This invention relates to one-step bulk or melt polymerizing monomers to make imide-containing polymers. In particular, it relates to making polyimides and polyimidesiloxanes by the direct polycondensation of molten monomers in the absence of a solvent.
Many types of polymers are made by polycondensation of molten monomers, including polyesters and polyamides. The absence of a solvent in bulk polymerizations reduces the cost of the polymerization because the steps of removing the solvent from the polymer and recovering it are eliminated. While aliphatic-aromatic and aromatic polyimides have been made in the melt from the salt in a two-step synthesis, the direct polycondensation of dianhydride and diamine would be the most economical route available.
Polyimides and polyimidesiloxanes are widely used in the electronics industry and in other industries as adhesives, coatings, and sealants, as well as for structural films and fibers. These polymers have good thermal stability, which makes them useful for high temperature applications where other polymers can not be used. However, because of their high glass transition temperatures or melting points, it was believed that polyimides and polyimidesiloxanes would degrade if made by bulk polymerization.